1. Field of the Invention
The present invention relates to a variable resistor comprising a contact member which slides along an arcuate resistive element, and more particularly, it relates to a variable resistor which comprises a clutch mechanism for transmitting rotation to a wiper forming the contact member.
2. Description of the Background Art
For example, U.S. Pat. No. 5,047,746 granted to Stilwell et al. describes a variable resistor.
The variable resistor (potentiometer) disclosed in the above U.S. Patent comprises an electrically insulating substrate, a resistive element arcustely extending on its one major surface, and a wiper which is affixed opposite the major surface of the substrate and rotatable with respect to the substrate.
A clutch mechanism enables the rotor to rotate the wiper so that a contact member formed on the wiper slides along the resistive element when the wiper rotates. As, a result value which is provided by this variable resistor is adjusted.
In the aforementioned variable resistor, the clutch mechanism is provided by a plurality of grooves which are formed at regular intervals and radially extend on the rotor, and a detent finger which is formed to integrally extend from the wiper. The detent finger has a free end which is engageable with any one of the grooves which are formed on the rotor.
However, the aforementioned detent finger is cantilevered with respect to the wiper. As a result the clutch action may be varied with the direction of the rotation which is transmitted from the rotor to the wiper, leading to inferior reliability of the clutch action.
Further, the contact member is provided in the aforementioned variable resistor by mounting a plurality of wires on a spring arm integrally extending from the wiper. Thus, the contact member is complicated in structure, and requires extensive efforts to obtain such a contact member. Consequently, the manufacturing cost for the variable resistor is disadvantageously high.